Our forecast for August is for temperatures to run one to three degrees hotter than the normal average of 79.8 Fahrenheit and for rain to run one to three inches higher than the normal of 2.93.
A hot August in 2020 would fit the recent mold. Over the past 10 years, seven Augusts have finished hotter than normal.
The forecast for a wet August has a bit of a cheat sheet thanks to next week’s expected close call with Hurricane Isaias. The National Weather Service is estimating close to an inch of rain early next week, but that value could be higher or lower pending the final storm track.
However, even if the storm completely misses our area, the pattern in early August should still enhance shower and storm chances for the Mid-Atlantic.
Below are the latest three sets of model system forecasts for rainfall over the next two weeks from the United States, Europe and Canada, all showing above-normal amounts:
The next two weeks should also still lean marginally hotter than normal, with better chances for 90s again later into the second week of August and into the third to fourth weeks. The three modeling systems, shown below, favor near to slightly above-normal temperatures through Aug. 15:
This morning’s latest NOAA CFS long-range model for the second half of August, shown below, calls for temperatures about one to two degrees hotter than normal with continued above-normal rainfall:
The main culprit behind this hot summer is a slow-developing La Niña pattern in the tropical Pacific Ocean, which is associated with cooling water temperatures in that region. As tropical Pacific waters gradually cool this summer, the global wind is slowing down, which enables hot, stagnant zones of high pressure to linger longer over the middle latitudes.
However, we should still have enough moisture flow into the region to give us plenty of rain chances, too. Similar circumstances evolved in the toasty summer of 2016, when a La Niña was also developing.